Combined cigarette maker and packer



March 31,I 1964'- sf. T. MoTLEY 3,126,999

COMBINED CIGARETTE MAKER AND PACKER Filed April. 25g 1961 2Sheets-Sheer.4 1

March 31, 1964 s. T. MOTLEY COMBINED CIGARETTE MAKER AND PACKER 2Sheets-Sheff(I 2 Filed April 25, 1961 l 1 1 l n 1 m l l l l l l l I l rl l 1 l l I l I l United States Patent O 3,126,999 COMBINED CIGARETTEMAKER AND PACKER Stanley T. Motley, Louisville, Ky., assigner to PhiiipMorris Incorporated, New York, NY., a corporation of Virginia Filed Apr.2S, 1961, Ser. No. 105,441 8 Claims. (Cl. 19d- 20) The present inventionis concerned with a combined cigarette maker and packer machine in whichcigarettes are mechanically collected from two or more cigarette makingmachines and delivered in selected groups to a cigarette packagingmachine.

It has been the practice in the making and packaging of cigarettes tomake the cigarettes on one machine, commonly referred to as Maker, formsa long continuous cigarette rod and the individual cigarettes arechopped off the end successively and collected in a tray. An operatorthen takes these trays of cigarettes and positions them on a so-calledPacker which selects and arranges the cigarettes in groups of twenty andapplies a wrapper to each group to form a common type of cigarettepackage. A standard packer has a capacity approximately equal to theoutput of two such makers.

The present invention comprises a combination machine in which theoutputs from a plurality of makers or cigarette formers areautomatically and mechanically com- -bined in a hopper from whichapparatus automatically divides out groups of cigarettes of the desirednumber for a package and inserts a group in each of successive pocketsof a continuous conveyor which delivers the respective groups from theconveyor pockets directly into the successive pockets of the rotarycompactor turret of a normal type packer from which they are transferredto successive pockets of the rotary folding turret and ulti- Imately aredischarged as complete individual packages. In other words the operationis completely automatic from the supply of tobacco and cigaretteIwrapper paper to the finished package. -Although the invention isillustrated in connection with and as receiving cigarettes directly`from a continuous rod forming type of machine and delivering themdirectly to lthe hopper for the conyeyor, the principles of theinvention are also applicable to receiving the output from any type ofmachine adapted to turn out iinished cigarettes. For example thecigarettes in the hopper may 'be delivered thereto directly frommachines of the kind which apply filter tips as a final operation ofcompletion of the cigarettes.

` The invention embodies further features and mechan-A ical deviceswhich contribute to the practicality and usefulness of the combination,one importan-t feature concerning the character of the continuousconveyor and its association with the other elements. As illustrated inthe embodiment of the invention shown in the drawings -the conveyorcomprises a continuous iiexible chain carrying spaced but closelyarranged buckets for receiving the groups of cigarettes from the hopperthe chain being intermittently advanced `step by step in timed relationwith the packer which embodies indexing turrets similarly operated.

Further objects and advantages will be apparent from a consideration ofa representative embodiment of the invention and accordingly theinvention comprises the features of construction combination of elementsand arrangement of parts which Iwill be exemplified in the constructionhereinafter set forth. In connection with the detailed description tofollow, reference should be had to the accompanying drawings in which:

FiG. l is a plan View showing diagrammatically the main units of thecomplete assembly;

FIG. 2 is an elevational view partly in section showing 3,126,999Patented Mar. 31, 1964 in particular the chain conveyor and itsassociation with the other units;

FIG. 3 is a cross-sectional View taken on the plane 5-3 of iFlG. 2;

FdG. 4 is a fragmentary horizontal section taken on approximately theplane 4 4 of FIG. 2 showing the mechanism for transferring the groups ofcigarettes from the `conveyor chain to the compacting turret;

iFlG. 5 is a fragmentary `View in elevation looking from the right inFIG. 4;

FG. 6 is a vertical elevation of a portion of one of the cigarettemaking machines connected into the hopper feed and looking in thedirection of the arrows 6-6 of FIG. 2 the casing being broken away andcertain inner portions being shown in section; and

FiG. 7 is a plan view of a section of the conveyor chain looking down onthe upper run of the chain in FiG. 2.

The general arrangement of a machine embodying the principles of theinvention is shown in FIGS. yl and 2. The main lfeatures or unitscomprise cigarette makers 10 and i1 each delivering its output ofcigarettes through `conveyor systems 12 and 113 respectively to a commoncollector in the form of a hopper 14 where cigarettes are divided out ingroups such as the usual twenty in number, and inserted in pockets in aflexible conveyor 15 which conveys the charges comprising -the groups ofcigarettes to a compactor turret lo where they are injected successivelyinto the pockets of the turret which carries the charges around to anassociated package folding turret 17 and the charges are transferred -topockets or arhors therein and indexed to a discharge position and leavethe apparatus fully packaged.

The units 10 and 11 each comprise means for making and deliverinUindividual completed cigarettes. The details thereof may vary dependingupon circumstances including the type of cigarette such as to whether itis a filter or non-filter cigarette and in referring to the units ditand 111 as cigarette makers it will be understood that the term isintended to mean an apparatus which cornpletes and delivers a cigarettein its final form ready for packaging. Accordingly the units maycomprise machines for attaching filter elements which include applying atipping paper or a machine for forming a continuous rod and successivelycutting off the individual cigarettes. 'Ihe present invention isparticularly advantageous in ernbodying cigarette makers of the lattertype and FIGS. 1 and 2 show the delivery ends of such type machines.

The present invention is not concerned with the details thereof `sincethey are -Well known in the art and reference is made lto the patent toMolins et al. 2,704,079 as showing a typical form of cigarette maker.rFor the present purposes it is sufficient to note that in the makeriltl cigarettes are successively cut off and fall on a belt conveyor 2t)entrained over suitable rolls, such as shown at 2.1, 22 and 23 in AFIGS.6. The housing for the conveyor 26 communicates with a housing of theconveyor unit 12 in which is mounted a belt conveyor 25 entrained overrolls 25 and Z7 the belt being operated through a. suitable driveconnection from the cigarette maker to the shaft 21S (FIG. 6) on whichis mounted the roll 26. As indicated in FG. 3 the mounting for roll 26may include a rear bearing 26a. The cigarettes are transferred fromconveyor belt 2t? onto belt 215 by suitable means such as the bladedreel 29 mounted on shaft 3i)` continuously rotated through a driveconnection from the cigarette maker. Cigarettes from the maker 10accordingly are delive ed into the collector hopper 14 as shown in FIG.2. The output from cigarette maker 11 is likewise delivered into thecommon hopper d4 by mechanism, including a. belt conveyor 31, like thatfor cigarette maker 10.

The hopper 14 may vary in construction and the details thereof form nopart of the present invention. In general, however, it may be like thatsho-wn in the patent to Bronander 1,847,060. Its principal 4featurescomprise an outer shell `4G and an inner abutment 41 with downwardly andoutwardly sloping sides whereby the cigarettes are caused to gravitateto the outer shell in both directions from the center. rl`he cigarettesthen are guided down three channels at each side, the one at the rightin FIG. 2 being shown in some detail. The three channels are defined bythe outer shell 40, two plate partitions 42 and 413 and the outersurface 44 of the central abutment 41. The three rows of cigarettestherefore gravitate downwardly into a measuring pocket 45. Theimmediately preceding description has been directed to the right side ofthe hopper as it appears in FIG. 2 but it will be understood that asimilar and symmetrical construction is located at the left side of thehopper. To encourage the feed of the three rows of cigarettes down thechannels and assist in maintaining an orderly arrangement of thecigarettes there may be located at the upper ends of the interveningplates 42 and i43, and also adjacent the walls 40 and 44, a series ofrollers `46 which preferably are iiuted or knurled. The rollers 46 areoscillated by suitable mechanism shown in general in FIG. 3 comprising achain or belt 47 entrained around a lower sprocket 48 mounted on shaft49 which is continuously rotated by means which will subsequently bedescribed. The chain extends over idler sprocket 50 and the upper end ofthe chain `47 is engaged around a sprocket 51 mounted on shaft `512..Secured also to the shaft 52 is a disc 53 to which is pivoted a pitman54 connected to and adapted to oscillate a lower disc or plate 55 towhich are connected rack elements, one engaging with rack gears mountedon Ithe shafts of the respective rollers 46 at the right and a similarrack and gear arrangement operates similar rollers at the left side inFIG. 2. The rack gears and rack elernents are not shown in the presentdrawings since the particular operating means is not important to thepresent invention. Reference, however, may be had to the said patent toBronander 1,847,060 `for a showing of the details of the operating meansfor the rollers 46, although for the purposes of the present inventionany suitable operating means will serve the purpose.

Measured groups of cigarettes are successively ejected from thecollector pocket 45 into pockets of a conveyor which transports therespective groups to the cigarette packaging unit of the completesystem. The character and detailed construction of the conveyor meansmay vary but the present drawings show a particularly advantageous andefiicient means for the purpose. It comprises essentially a pair ofchains 6@ and 69' as shown particularly in FIG. 7 between which aremounted tubular conveyor pockets or boxes 61. The pockets are eachcomprised of an outer shell of sheet metal and the pockets arerectangular in cross section and open at each end. The pockets aresecured to the chains by any suitable means which in the presentembodiment comprises providing appropriate links with an integral ear 62extending at right angles to the link and secured to a strap 62a on thebottom of the corresponding pocket 61. As shown at the right in FIG. 2the `chains are entrained around a pair of spaced sprockets 613 fixed toshaft 64 which receives an intermittent step by step motion in a counterclockwise direction as will be described in more detail below. The upperrun of the two chains advances over upper pairs of sprockets 65, 66 and`67 down around a pair of large sprockets 68 and lower sprockets 69 and70, and eventually over sprockets 71 and 72 adjacent the main sprockets63 the sprockets 71 and 72 providing a straight horizontal short runwherein the cigarette groups are successively transferred to thecompactor turret l16 likewise mounted on the shaft 64. The details ofthe transfer mechanism will be described below, but for the present itmay be noted that it embodies a reciprocatory plunger indicateddiagrammatically at in FIG. l. At the longer spans of the conveyor thechains may be supported by suitable guides such as that indicated at 76in FIG. 2.

The mechanism for transferring charges or groups of cigarettes from themeasuring pocket 45 into successive pockets 611 of the conveyor chainwill now be described. The mechanism includes a plunger 80 slidablymounted in the pocket 45 connected to a plunger rod 81 extending from across head `82 which preferably has an auxiliary guide and support onsuitable means such as the rod 83 fixed in the hopper housing. The crosshead 82 is connected by link 84 with a lever 85 pivoted on the mainframe or housing at 86 the lower end of lever 85 being connected througha link `37 with a bell crank 88 pivoted at 89 on a fixed bracket 90 atthe rear of the machine. The pivot mounting of link 87 on the lower endof bell crank arm S8 may be adjustably secured at a selected positionalong the slot 83a to vary slightly the stroke of the plunger 80. Thefront arm 911 of the bell crank 88 has a roller 92. riding on the cam93` secured on the shaft 49. The roller 92 is held in engagement withthe cam 93 by a tension spring 94. The shaft 49' is continuously drivenfrom any suitable connection in the driving mechanism for the cigarettepackaging unit as indicated somewhat d-iagrammatically at 95 in FIG. 2.The conveyor chain `15 is also driven from the cigarette packagingmachine as heretofore stated but is directly geared to be indexed oradvanced intermittently with the compactor turret 116. Through the cammeans 93, the transfer mechanism is likewise operated intermittently andsince it derives its drive from the same source as the conveyor chain,the two elements can be properly associated in timed relation. Morespecifically in the operation of the conveyor chain it has successiveperiods of dwell in each of which a conveyor pocket 61 is located inaxial alignment with the measuring pocket 45 of the hopper' as indicatedparticularly in iFIG. 3 and during that period of dwell the cam 93serves to advance the plunger 80 and project the group of cigareteslfrom the pocket 45 into the particular conveyor pocket 61.

The cigarette packaging unit depicted at the right in FIGS. l and 2comprises a conventional machine well known in the art and only so muchof the details are shown as will indicate the relation and connection ofthe unit to the conveyor 15. Cigarette packing machines, or Packers asthey are commonly called, of the type embodied in the presentcombination machine are shown and described in various prior patentssuch as in particular the patents to Bronander 1,926,192 and Metz2,783,596 to which reference may be had for details. In general,however, such machines embody two associated turrets corresponding tothose indicated at 16 and 17 in FIGS. l and 2 of the present drawings.The turret 16 is commonly referred to as the compactor turret and theturret 17 as the folding turret. Each turret has twelve positionscorresponding to the positions on a clock and commonly referred to bythe corresponding Roman numerals I to XII. As viewed in FIG. 2 turret 16rotates counterclockwise and turret 17 rotates clockwise. The turretsare indexed successively in exact timed relation and have periods ofdwell after each advance. The compactor turret 16 which has twelvepockets 100 receives a group of cigarettes in each pocket when itarrives at the position IX. The folding turret 17 has twelve hollowarbors 101 and from stations I to III the tin-foil or inner wrapper isfolded around the respective arbor. From stations III to VI the outerwrapper or pouch sheet is applied and folded. As position IX of turret17 the hollow arbor around which the wrappers have been folded comesinto registration with a pocket on the compacting turret and a plunger102 at the rear (see FIG. 1) transfers the group of cigarettes from apocket 100 in the turret 16 into the corresponding hollow arbor 101 ofthe folding turret 17. From station IX to station XII the group ofcigarettes is pushed into contact with the bottom of the wrapperpreformed on the arbor and continued movement slides the cigarette groupon through carrying with it the wrapper, and the package, open at oneend, is picked up and conveyed through mechanism which completes thefolding at the open end. These latter operations are standard operationsin cigarette packaging machines and are described and illustrated forexample in the patent to Bronander 1,926,192 noted above.

A suitable mechanism for operating the plunger 75, heretofore mentioned,for transferring the groups of cigarettes from pockets 61 of theconveyor chain into pockets 160 of the compactor turret 16 is shown inFIGS. 4 and 5. It comprises a cam 110 mounted on a continuously rotatedshaft 111 driven from the operating means for the packaging machine. Theshaft 111 is rotated by a suitable drive connection at the same rate asshaft 49 upon which is mounted the cam 93 for operating the plunger`Si). Cam 110 is engaged by a follower 112 carried by lever 113 pivotedat 114 on a fixed bearing support 115, the follower being held inengagement with the cam by a tension spring 116 connected to the upperend of lever 113. A link 117 connects the extreme upper end of lever 113to a cross head 118 slidable in a suitable fixed guideway 119. Theplunger 75 is connected to cross head 113 by a pitman 120. In theretracted position shown, plunger 75 rests within an opening in a fixedmember 121 and in its forward movement pushes the group of cigarettesfrom the registering chain pocket 61 into the likewise registeringpocket 100 in turret 16.

FIG. 2 shows a means for tensioning the chains 6l), 60 of conveyor 15and adjusting the relation of the pockets 61 with respect to the hopperopening 45 during the period of dwell of the conveyor. The front bearingsupport for the shaft for sprockets 130 which engage the lower runs ofthe chains is contained in a block 131 slidable in a pair of guides 132.The slide carries a lug 133 through which extends a screw 134 threadedinto lug 135 which is fixed to the stationary plate 135er on which theblock 131 is slidable. The block 131 is clamped in adjusted position byset screw 136 extending through a slot in the slide. The opposite orrear end of the sprocket shaft is similarly mounted at the rear. Alsothe shaft for the upper sprockets 137 is mounted similarly to the shaftfor the lower sprockets 130. It will be apparent that moving bothsprockets up or down will shift the dwell positions of the chain pockets61 with respect to the fixed measuring pocket 45 so as to insureaccurate registration during the transfer of a group of cigarettes fromthe collector pocket into a chain pocket 61.

It should be understood that various changes may be made in the abovedescribed combination apparatus and further `or different embodiments ofthe invention could be made without departing from the scope thereof,and it is intended that all matter contained in the above desciiption orshown in the accompanying drawing shall be interpreted as illustrativeand not in a limiting sense.

I claim:

l. A flexible continuous conveyor system for automatically transferringarticles said system having an article receiving station and an articledelivery station with advancing and return runs of the conveyor betweenstations, said conveyor comprising a pair of laterally spaced chainswith article pockets spaced therealong between the chains, sprocketmeans for supporting said chains, driving means for intermittentlyadvancing said conveyor with an intervening period of dwell betweenadvances, and means for adjusting the tension of the chains and theposition of the corresponding pocket relative to one of said stationsduring the periods of dwell comprising a pair of laterally spacedsprockets engaging respectively the two chains in the advancing run, anda pair of laterally spaced sprockets engaging respectively the twochains 6 in the return run, and supporting means of each of said pairsof sprockets including means for adjusting the positions of thesprockets toward or away from the respective chains.

2. A machine comprising in-combination, a cigarette packaging apparatusofthe type having a rotary compactor turret with peripherally spacedpockets, a cigarette supply hopper spaced a substantial distance fromsaid packaging appartus, a continuous conveyor having pockets thereineach adapted to receive a group of cigarettes therein, said continuousconveyor being arranged to bring successive pockets thereof intoregistry with successive pockets respectively of said turret, a firsttransfer means for inserting measured groups of cigarettes from saidhopper into successive pockets in said continuous conveyor, a secondtransfer means for delivering Athe groups of cigarettes from the packetsof the conveyor to the respective pockets of said turret, and drivemeans for operating said continuous conveyor and said first and secondtransfer means in timed relation with each other and with said packagingapparatus.

3. A combination machine comprising, a cigarette packaging -apparatus ofthe type having a rotary compactor turret with peripherally spacedpockets, a cigarette hopper spaced Ifrom said packaging apparatus, acontinuous flexible conveyor having pockets therein each adapted toreceive a group of cigarettes therein, said continuous conveyor ibeing.arranged to deliver the groups from said hopper to said compactorturret, a first transfer means for inserting measured groups ofcigaettes from said hopper into successive pockets in said continuousconveyor, a second transfer means for discharging the groups from thesuccessive pockets of the continuous conveyor into successive pockets ofthe compactor turret, and drive means for operating said continuousconveyor and said first and second transfer means in timed relation witheach other and with said compactor turret.

4. A combination machine comprising, a cigarette packaging apparatus ofthe type having a rotary compactor turret intermittently advanced withintervening periods of dwell and having peripherally spaced pockets, acommon cigarette supply hopper spaced from said packaging apparatus, acontinuous flexible conveyor having open ended pockets therein eachadapted to receive a group of a predetermined number of cigarettestherein, said continuous conveyor being arranged to deliver the groupsfrom said hopper to said compactor turret, a first reciprocatory plungermeans for inserting measured groups of the predetermined number ofcigarettes from said hopper into successive pockets in said continuousconveyor, a second reciprocatory plunger means for discharging thegroups from the successive pockets 4of the continuous conveyor intosuccessive pockets of the comp-actor turret, and drive means foroperating said continuous conveyor and said first and second plungermeans in timed relation with each other and with said compactor turret,said continuous conveyor being advanced concurrently with said turret,and said first and second plunger means being operated during therespective periods of dwell.

5. A machine comprising, a cigarette packaging apparatus of the typehaving a rotary compactor turret with peripherally spaced pockets, acigarette hopper spaced from said packaging apparatus, a flexiblecontinuous conveyor having pockets therein each adapted to receive agroup of cigarettes therein, rotary mounting elements for supportingsaid flexible continuous conveyor including a rotary element mountedconcentrically with said turret `and connected to rotate therewith, saidcontinuous conveyor being arranged to deliver `the groups of cigarettesfrom said hopper to said compactor turret and to bring successivepockets in said continuous conveyor into registration respectively withsuccessive pockets in said turret, a first transfer means for insertingmeasured groups of cigarettes from said hopper into successive pocketsin said continuing conveyor, a second transfer means for discharging thegroups of cigarettes from the successive pockets of the continuousconveyor into successive pockets of the compactor turret, and drivemeans for operating said continuous conveyor and said rst and secondtransfer means in timed relation with each other and with said compactorturret.

6. In combination, an article packaging apparatus, an article supplyhopper, a continuous conveyor comprising a pair of flexible chains withopen ended tubular pockets extending across the chains and spacedtherealong, sprockets for supporting said chains, said pockets eachadapted to receive therein a group of a predetermined number of saidarticles, said continuous conveyor being arranged to deliver lthe groupsfrom said hopper to said packaging apparatus, a first transfer means forinserting measured groups of articles from said hopper into successivepockets in said continuous conveyor, a second transfer means fortransferring the groups from the successive pockets of said conveyor tosaid packaging apparatus, and drive means for operating said continuousconveyor and said rst and second transfer means in timed relation witheach other and with said packaging apparatus.

7. A machine comprising, a cigarette packaging apparatus of the typehaving a rotary compactor turret with peripherally spaced radialpockets, a cigarette hopper spaced from said packaging apparatus, aeXible continuous conveyor having transverse tubular pockets carriedthereby each adapted to receive a group of cigarettes therein, rotarymounting elements for supporting and guiding said ilexi'ble continuousconveyor including means lfor directing said conveyor during a portionof its travel from said hopper radially of said turret to bringsuccessive pockets in said continuous conveyor into registrationrespectively with successive pockets in said turret, a irst transfermeans for inserting measured groups of cigarettes from said hopper intosuccessive pockets in said continuous conveyor, a second transfer meansfor discharging the groups from the successive pockets of the continuousconveyor into successive pockets of the compactor turret, and drivemeans for operating said continuous conveyor and said first and secondtransfer means in timed relation with each other and with said compactorturret.

8. A machine comprising, a cigarette packaging apparatus of the typehaving a rotary compactor turret with peripherally spaced radialpockets, a cigarette hopper spaced from said packaging apparatus, aflexible continuous conveyor having transverse tubular pockets carriedthereby each adapted to receive a group of cigarettes therein, rotarymounting elements for supporting and guiding said flexible continuousconveyor including a rotary element mounted concentrically with saidturret and connected to rotate therewith, and means for directing saidconveyor during a portion of its travel from said hopper radially ofsaid turret to bring successive pockets in said continuous conveyor intoregistration respectively with successive pockets in said turret, a irsttransfer means for inserting measured groups of cigarettes from saidhopper into successive pockets in said continuous conveyor, a secondtransfer means for discharging the groups from the successive pockets ofthe continuous conveyor into successive pockets of the compactor turret,and drive means for operating said continuous conveyor, said first andsecond transfer means and said compactor turret intermittently and intimed relation With each other.

References Cited in the file of this patent UNITED STATES PATENTS552,716 Matthiesen Jan. 7, 1896 1,326,187 Donelly Dec. 30, 19191,847,060 yBronader Feb. 23, 1932 1,870,533 Scott et al Aug. 9, 19321,998,382 Nel Apr. 16, 1935 2,330,000 Molins Sept. 2l, 1943 2,745,410Molins May 15, 1956 2,783,596 Metz Mar. 5, 1957 UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Patent N0. 3, 126,999 March 31, 1964 vStanley T. Motley It ie hereby eertified that errer eppeere in the ebevenumbered pet` ent requiring correction and that the said Letters Patentshould read as corrected below.

Column 1, line 16, before "forms" insert which column 4, line 4l, for"cigaretes" read cigarettes line 70, for "As" read At column 6, line 17,for "packets" read pockets line 30, for "cigaettes" read cigarettescolumn 8, line 31, for "Matthiesen" read Matthiessen after line 31,insert after line 37, insert 2,772,005l Dubin --Nov 27, 1956 Signed andsealed this 4th day of August 1964.

(SEAL) Attest:

ERNEST W, SWIDER EDWARD J., BRENNER Attesting Officer Commissioner ofPatents

1. A FLEXIBLE CONTINUOUS CONVEYOR SYSTEM FOR AUTOMATICALLY TRANSFERRINGARTICLES SAID SYSTEM HAVING AN ARTICLE RECEIVING STATION AND AN ARTICLEDELIVERY STATION WITH ADVANCING AND RETURN RUNS OF THE CONVEYOR BETWEENSTATIONS, SAID CONVEYOR COMPRISING A PAIR OF LATERALLY SPACED CHAINSWITH ARTICLE POCKETS SPACED THEREALONG BETWEEN THE CHAINS, SPROCKETMEANS FOR SUPPORTING SAID CHAINS DRIVING MEANS FOR INTERMITTENTLYADVANCING SAID CONVEYOR WITH AN INTERVENING PERIOD OF DWELL BETWEENADVANCES, AND MEANS FOR ADJUSTING THE TENSION OF THE CHAINS AND THEPOSITION OF THE CORRESPONDING POCKET RELATIVE TO ONE OF SAID STATIONSDURING THE PERIODS OF DWELL COMPRISING A PAIR OF LATERALLY SPACEDSPROCKETS ENGAGING RESPECTIVELY THE TWO CHAINS IN THE ADVANCING RUN, ANDA PAIR OF LATERALLY SPACED SPROCKETS ENGAGING RESPECTIVELY THE TWOCHAINS IN THE RETURN RUN, AND SUPPORTING MEANS OF EACH OF SAID PAIRS OFSPROCKETS INCLUDING MEANS FOR ADJUSTING THE POSITIONS OF THE SPROCKETSTOWARD OR AWAY FROM THE RESPECTIVE CHAINS.